Error message importing MHX2 in 2.8
The add-on hasn't been properly updated for Blender 2.80. It tries to access color_space on an Image Texture node, which is no longer part of ShaderNodeTexImage in Blender 2.80. It used to be in Blender 2.79b and before.

The proper way of accessing the color space settings is to retrieve the Image object referenced by ShaderNodeTexImage which has the colorspace_settings. 

The issue has already been reported to the developer.